This invention relates to electric door lock mechanisms and more particularly to fail-secure and fail-safe lock mechanisms.
In high security areas such as banks, computers rooms, museums, etc., electrically actuated door locks of either the fail-secure or fail-safe type are employed. For such applications, it is often preferable that the lock mechanism be mounted in a conventional, narrow door stile or frame member and, therefore, it is necessary that the lock be relatively narrow, shallow, and compact.
In fail-safe electric door locks, a locking condition is attained upon energizing the electric lock mechanism and an unlocking condition is attained by deenergizing the electric lock mechanism. Thus, a power failure or the like results in an unlocked condition, i.e., fail-safe. Conversely, in fail-secure electric door locks, a locking condition is attained upon deenergizing the electric lock mechanism and an unlocking condition is attained by energizing the electric lock mechanism. Thus, a power failure or the like results in a locked condition, i.e., fail-secure. In both fail-secure and fail-safe electric door locks, it is desirable to provide automatic deadlocking of the bolt in a projected "locking" position to resist jimmying of the lock.
It is a principal object of this invention to provide an improved door lock mechanism that attains both fail-secure and fail-safe operation.
A further object of the invention is to provide an electric door lock mechanism for fail-secure and fail-safe applications which automatically deadlocks in the projected locking position.
A still further object of the invention is to provide an electric door lock mechanism for fail-secure or fail-safe applications with manual mechanical retraction of the bolt in a fail-secure application and manual mechanical projection of the bolt in a fail-safe application.
Yet another object of the invention is to provide fail-secure and fail-safe electrical door lock mechanism that is economical to manufacture, versatile and durable in use, and refined in appearance.
All other objects will be in part obvious and in part pointed out more in detail hereinafter.